Another Jet Flight
8) Here's a slight variation from our previous example: A small
jet made a 1285-mile flight in 5 hours. Its fastest speed was
constant during the first two hours, but then dropped to 30 mph
slower during the 3rd hour, 40 mph slower (than the 1st hour)
during the 4th hour, and 55 mph slower (than the 1st hour) during
the last hour. Find the speed for each hour.
2x + (x -30) + (x -40) + (x -55) = 1285 ("x" = the fastest
speed. "2x" = 2 hours of the fastest speed.)
5x -125 = 1285
5x = 1410
x = 282
Since "x" equals 282 (mph), then that is the speed of the
jet during the first two hours, and two hours at that speed was a
distance of 564 miles. When we plug the value of x into the x-variable
for all the terms, here's what we come up with:
564 (2x)
252 (x-30)
242 (x-40)
227 (x-55)
-----------------
1,285 (total miles)